Using Java variables in Xtags select

Hi,
  I am using xtags library in a JSP and am having
trouble using Java variables while selecting XML
nodes. The XML to be parsed is:

<xtags:parse id="parsed">
<parent id="1">
   <child id="c1">
       <class grade="art"/>
       <class grade="science"/>
   </child>
   <child> ... </child>
</parent>
</xtags:parse>

<xtags:forEach context="<%=parsed%>"
       select="//child[@id=<%=child_id%>/class">
  ...
</xtags:forEach>

Where child_id is a Java variable defined in the JSP.

The above code throws an exception complaining about
'<' in the expression. Even after escaping the
character it does not work. I even tried with indexing
like, 

select="//child[i]/class"

where i is the index of the line. The problem is the
above select code returns all the child nodes instead
of the index=i. Seems like its null or something. 

Help is highly appreciated.

Thanks,
-Ashish

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